Preparation of unsaturated aldehydes



ryn. a,

United States Pteir Patented Sept. 1, 1959 2,902,515 PREBARATION OFUNSATURATED ALDEHYDES Marc Moutavon; Basel, andGabriel Saucy, Neuewelt,

Munclienstein, Switzerland, assignorsto Holimanng4?! Roche Inc., Nutley,N.J., a corporation of New ersey N Drawing. Original application August22, 1956, Se rial No. 605,462. Divided and this'application March 10,1958, Serial No. 720,034

Claimspriority, application Switzerland September 2, 19.55

7 Claims. (Cl. 260-598) This invention relates to novel processes ofmaking organic compounds. More particularly, the invention is concerned,in one of its aspects, with novel processes and novel intermediates formaking Dali-unsaturated aldehydes; and in another of its aspects, withnovel processes for making unsaturated ketones.

The novel processes provided by the invention for making ugh-unsaturatedaldehydes can be characterized broadly as comprising a stage wherein a3,3-disubstituted allyl halide. is reacted Withyan alkali metal salt ofa nitronic acid, thereby forming a nitronic acid ester; and a furtherstage wherein said nitronic acid ester is decom posed, thereby formingan r p -unsaturated aldehyde.

In a more limited embodiment, the invention relates to a process whichcomprises reacting a 3,3-disubstituted allyl halide having. the. FormulaI wherein the symbol X represents a halogenselected from the groupconsisting of chlorine and bromine, and the symbol group B=C= representsa disubstituted methylene radical selected from the group consisting ofdialkylmethylene, alkylalkenylmethylene, cycloalkylidene andcycloalkylidene substituted. in the ring. only by at least onesubstituent of the class consisting of lower alkyl, lower alkoxy, loweralkanoyloxy, oxo and ketalized oxo, with an alkali metal salt of a loweralkanenitronic acid, thereby forming a nitronic acid. ester having theFormula H (II) 0 R B=C=CH-OHaOl T=( R wherein the symbol R represents alower alkyl radical and the symbol R representsa member selected fromthe group consisting of hydrogen and lower alkyl radicals, the sum ofthe carbon atoms in R and R being less than 6; and the symbol group B=C=has the same meaning indicated above; and decomposing said nitronic acidester (II), thereby forming an a,/8-unsaturated aldehyde having theFormula III (III) o B=o=oH-i3-H wherein the symbol group B=C= hasthesame meaning indicated above.

Illustrative 3,3-disubstituted allyl halides, Formula I above, suitablefor use in the processes of the invention include: 3,3-dialkylallylhalides [alkyl being understood to include saturated hydrocarbonradicals with cyclic structure, such as cycloalkyl-alkyl, e.g.cyclohexylpropyl], e.g. 3-methyl-2-buten-l-yl chloride [alternativenomenclature: 3,3-dimethylallyl chloride], 1-bromo-3,7 dimethyl-Z-octene[alternative nomenclature: 3'-methyl- 3-(4-methy1-l-pentanyl)-allylbromide], tetrahydrofarnesyl bromide [alternative nomenclature:3-methyl-3-(4,8- dimethyl-1-nonanyl)-allyl bromide], and the like;3-alky1- 3-alkenylallyl halides [alkenyl being understood to includeboth alka(mono)enyl radicals and alka(poly)enyl radicals as wellasolefinic hydrocarbon radicals with cyclic structure, such ascycloalkybalkenyl, e.g. 3-cyclohexylidene-propyl], e.g.l-bromo-3,7-dimethyl2,6 octadiene [alternative nomenclature: 3-methyl3'-(4-methyl-3-penten-l-yl)-allyl bromide],l-bromo-3-methyl-6-cyclohexylidene-Z-hexene [alternative nomenclature:3-methyl-3-(3- cyclohexylidene-propyl)-allylbromide], 1-chloro-3,7,9-trirnethyl-Z,G-decadiene- [alternative nomenclature: 3-methyl-3-(4}6-dimethyl-3-hepten-1-yl)-allyl chloride] farnesyl bromide,phytyl' chloride, and the like; and 2-cycloalkylideneethyl halides, andZ-cycloalkylideneethyl' halides substituted only in-the-nucleus by atleast one sub stituent of the class consisting of lower alkyl, loweralkoxy, lower alkanoyloxy, oxo and ketalized ozo; e.g.3-cyclohexylideneethyl bromide, 3-cyclopentylideneethyl chloride,3-cycloheptylideneethyl' bromide, 2-(4-methyl- 1 cyclohexylidene)ethylchloride, 2 (2,6,6 triinethyl l cyclohexylidene)ethyl bromide, 2 (2-isopropyl 5 methyl- 1' cyclohexylidene)ethyl bromide, 2- (2,2,6,6tetramethyl l cyclohexylidene)ethyl bromide, 2 (4 methoxy lcyclohexylidene)ethyl chloride, 2 (4 acetoxy 1 cyclohexylidene)ethylbromide, 2 (4 acetoxy 2,6,6 trirnethyl 1 cyclohexylidene)ethyl bromide,2'- (4 0x0 1 cyclohexylidene)ethyl chloride, 2 (4,4- dimethoxy 1cyclohexylidene)ethyl bromide, and 2 (4 ethylenedioxy-2,6,6-trimethyl-1-cyclohexyli'dene) ethyl bromide, and the like.

Whereas chlorides and bromides are specifically identified in thepreceding illustrations, it should be understood that fluorides andiodides can also be used.

Illustrative alkali metal salts of nitronic acids which can be usedinclude especially alkali metal lower alkanenitronates, e.g. potassiummethanenitronate, potassium ethanenitronate, sodium-Z-propanenitronate,potassium-1- propanenitronate, lithium-2-n-butanenitronate, and thelike. Whereas the alkali metal salts of any nitronic acid (i.e., aprimary or secondary organic nitro compound capable of existing in theaci-form) can be used, it ispreferred to use an alkali metal salt (andpreferablya sodium or potassium salt) of a lower alkanenitronic acid.Ondinarily, salts of secondary nitronic acids (e.g. 2-propanenitronicacid) are preferred to those of primary nitronic acids (e.g.1'-propanenitronic acid).

The reaction is advantageously eflfected by mixing the all'ylic halidewith the alkali metal nitronate in the presence of a diluent, attemperatures between about --10 C. and about C. In most cases, dependingupon the starting materials used and the diluent, the preferred range oftemperature is between'about 0 C. and about 50 C. Suitable diluentsinclude, for example, water;-

monohydric and polyhydric alcohols, e.g. ethanol, isopropanol,t-butanol, monoand diethyleneglycol; ethers, e.g. dioxan,tetrahydrofuran and diethyleneglycol ethyln-butyl diether; amides, e.g.dimethylformamide; acetals, e.g. methylal; nitriles, e.g. acetonitrile;and the like. Ordinarily, it is preferred to-use an inert diluent, i.e.one which reacts with neither the allylic halide reactant, the alkalimetal nitronate reactant, the nitronic acid ester in termediate nor thea,,8-unsaturated aldehyde product. However, in certain instances, asdiscussed below, it is desirable to employ diluent material whichreacts, at least in part, with the aldehyde product.

In one mode of operation which has been found suitable, the alkali metalnitronate is prepared by reacting a lower nitroalkane with an aqueoussolution of an alkali metal hydroxide (preferably aqueous NaOH oraqueous KOH), and the thus obtained aqueous solution ofalkali metallower .alkanenitronate is mixed with the allylic halide, in the presenceof a diluent, at temperatures between about 0 C. and about 50 C.

In another advantageous mode of execution, the alkali metal nitronate isprepared by mixing a lower nitroalkane with an alkali metal loweralkoxide (e.g. potassium-t-butoxide dissolved in t-butanol), and thethus obtained alcoholic solution or suspension of the alkali metalnitronate is mixed with the allylic halide, if desired in the presenceof additional diluent, at temperatures between about C. and about 50 C.

Still another procedure which has been found suitable is to prepare thealkali metal nitronate by introducing the nitro compound into asuspension of finely divided anhydrous alkali metal hydroxide in anacetal (e.g. methylal) or an ether (e.g. diethyleneglycol ethyl n-butyldiether), and stirring the mixture obtained, at about room temperature,with the allylic halide.

Depending upon the particular reactants and diluents employed, thereaction mixture either takes the form of a homogeneous system orseparates into layers. In the latter case, it is advantageous to obtainintimate contact between the phases by thorough mixing.

Because of thermal influences, even at the relatively low temperaturesemployed, the nitronic acid ester formed at an intermediate stagedecomposes spontaneously, thereby yielding the desired a,,8-unsaturatedaldehyde.

In one preferred embodiment, the invention provides a process of makinga monoolefinic c p-unsaturated aldehyde which comprises mixing a3-alkylcrotyl halide with an alkali metal salt of a lower alkanenitronicacid in the presence of an inert liquid diluent at temperatures betweenabout C. and about 50 C. For example, by stirring1-brorno-3,7-dimethyl-2-octene [alternative nomenclature:3-(4-methyl-l-pentanyl)-crotyl bromide] withpotassium-2-propane-nitronate in the presence of a mixture ofacetonitrile and water at temperatures between about 40 C. and about 45C., 3,7-dimethyl-2-octen-l-al is obtained in good yield.

In a second preferred embodiment, the invention provides a process ofmaking a polyolefinic a,/8-unsaturated aldehyde which comprises mixing a3-alkenylcrotyl halide with an alkali metal salt of a loweralkanenitronic acid in the presence of an inert liquid diluent attemperatures between about 15 C. and about 50 C. For example, bystirring 1-bromo-3,7,9-trimethyl-2,6-decadiene [alternativenomenclature: 3-(4,6-dimethyl-3-hepten- 1-yl)crotyl bromide] withpotassium-l-propanenitronate in the presence of a mixture of water andisopropanol at temperatures between about 40 C. and about 45 C., 3,7,9-trirnethyl- 2,6 decadien-l-al is obtained in good yield.

In a third preferred embodiment, the invention provides a process ofmaking a cyclic a,;3-unsaturated aldehyde which comprises mixing acyclic allylic halide selected from the group consisting ofZ-cycloalkylideneethyl halides and their nuclear substituted derivativeswherein the substituents are selected solely from the class consistingof lower alkyl, lower alkoxy, lower alkanoyloxy, 0x0 and ketalized 0x0with an alkali metal salt of a lower alkanenitronic acid in the presenceof an inert liquid diluent at temperatures below about 40 C. Forexample, by reacting 2-(4 acetoxy 2,6,6 trimethyl-lcyclohexylidene)ethylbromide with potassium-Z-propanenitronate in the presence of a mixtureof water and dimethylformamide at temperatures between about C. andabout C., 4 acetoxy-2,6,6-trimethyl-l-cyclohexylideneacetaldehyde isobtained in good yield.

As indicated previously, it has been found to be desirable, in certainembodiments of the invention, to use a diluent which is itself reactivewith the a,,B-unsaturated aldehyde formed by reaction between theallylic halide and the alkali metal nitronate. Thus, it has been foundthat acyclic multiply unsaturated ketones, containing within theirstructure the fundamental carbon skeleton characteristic ofpseudoionone, can be made by reacting first certain 3-alkenylcrotylhalides with alkali metal nitronates and by adding then an alkalineagent in the presence of certain lower aliphatic ketones. The acyclicmultiply unsaturated ketones so produced are readily cyclized upontreatment with acidic reagents, yielding 11- and ionones and homologsand analogs thereof. Thus, in still another of its preferredembodiments, the invention provides a process of making an unsaturatedcyclic ketone which comprises mixing a 3-alkenylcrotyl halide having theFormula IV.

RRRR Ha wherein each of the symbols R represents a member selected fromthe group consisting of hydrogen and lower acyclic hydrocarbon radicalsat temperatures between about 10 C. and C., with an alkali metal salt ofa lower alkanenitronic acid, in the presence of a ketone having theFormula V wherein Z represents hydrogen or an acyclic hydrocarbonradical and Y represents an acyclic hydrocarbon radical, the sum of thecarbon atoms in the radicals Z and Y being less than 6, adding analkaline agent thereby producing an unsaturated acyclic ketone havingthe Formula V1 RRRROH; ZO

wherein the symbols R, Z and Y have the same meanings indicated above;and treating said unsaturated acyclic ketone (VI) with an acidiccyclizing agent, thereby obtaining a cyclic unsaturated ketone havingone of the following Formulas VII and VIII wherein the symbols R, Z andY have the same meanings indicated above.

Suitable 3-alkenylcrotyl halides, Formula IV above, for use inpracticing the last mentioned embodiment of the invention include, forexample, 1-bromo-3,7-dimethyl- 2,6-octadiene,1-bromo-3,6,7-trimethyl-2,6-octadiene, lchloro-3,7-dimethyl-2,G-nonadiene, 1 brorno 3,7,9trimethyl-2,6-decadiene and the like.

Suitable ketones, Formula V above, for use in practicing the lastmentioned embodiment of the invention include, for example, acetone,methyl ethyl ketone, diethyl ketone, di-n-propyl ketone, methyl vinylketone, methyl propargyl ketone and the like.

The 3,3-disubstituted allyl halide starting materials of the invention,Formula I above, can, in general, be made by ethinylating a ketonehaving the formula thereby obtaining an acetylenic tertiary carbinolhaving the formula and halogenating the latter, for example. bytreating. with phosphorus tribromide in an inert solvent or anhydroushydrogen chloride in an inert solvent, or by treating with concentratedaqueous hydrochloric acid or concentrated aqueous hydrobromic acid. (Inthe above formulas, the symbol group B=C= has the same meaning indicatedpreviously.)

The a,/8-unsaturated aldehydes and the cyclic unsaturated ketonesobtained by the processes of the invention are useful in erfumery asodor-imparting agents, and in organic synthesis as intermediates in thepreparation of vitamin A and carotenoids.

The invention is further disclosed in the following examples, which areillustrative but not limitative thereof.

Example 1 g. of 2-nitropropane were added slowly, while stirring andcooling to 1020 C., to a mixture of 6.9 g. of solid potassium hydroxide(containing 85% by weight KOH), 7 ml. of water and 30 ml. of t-butanol.The solution thus obtained was mixed quickly with a solution of 21.7 g.of l-bromo-3,7-dimethyl-2,6-octacliene in 60 ml. of t-butanol, and themixture was stirred for several hours at- 25 C., with cooling asnecessary, potassium bromide being thereby precipitated. Then 200 ml.of. water were added and the mixture was extracted with petroleum ether.The petroleum ether extract was washed with cold aqueous 1 N sodiumhydroxide solution. and with water, dried, over sodium sulfate, and thenthe solvent was distilled off. There were thus. obtained 15.2 g. of3,7-dimethyl-2,6-octadien-l-al, having an absorption maximum in theultraviolet spectrum at 232 m (in petroleum ether). The material waspurified by distillation in vacuo, thereby yielding a colorless formhaving B.P. 102104 C., n =1.482.

Example 2 10 g. of 2-nitropropane were added slowly, while stirring andcooling to 25 C., to a mixture of 5.6 g. of solid sodium hydroxide(containing 85% by weight NaOI-I), 10 ml. of water and 30 ml. ofdimethyl-formamide. The resulting mixture was mixed with a solution of21.7 g. of 1-bromo-3,7-dimethyl-2,6-octadiene in 90* ml. ofdimethylformarnide. The reaction mixture was stirred for 15 hours at -30C. and was, then worked up in the manner indicated in Example 1. Therewere thus obtained 14.3 g. of 3,7-dimethyl-2,6-octadien-l-al.

Example 3 10 g. of 2-nitropropane were introduced slowly at 25 C., whilestirring, into a mixture of 2.8 g. of lithium hydroxide (85% pure), 10ml. of Water and ml. of dimethylformamide, and the stirring wascontinued for 30 minutes. Then a solution of 21.7 g. of 1-bromo-3,7-dimethyl2,6-octadiene in 90 ml. of dimethylformamide was added. Thereaction mixture was stirred for 15 hours at 25 -30 C., and was thenworked up as in Example 1, yielding 14.6 g. of3,7-dirnethyl-2,6-octadien- 1-al..

Example 4 A solution of 17.3 g. of 1-chloro-3,7-dimethyl-2,6- octadienein 60 ml. of dimethylformamide was reacted, in

6 the manner described in Example 1, with a solution of 10 g. of2-nitropropane and 6.9 g. of potassium hydroxide pure) in 7 ml. of waterand 30 ml. of dimethylformamide. Upon working up the reaction mixture asin Example 1, there were obtained 14 g. of 3,7-dimethyl-2,6-octadien-1-al.

Example 5 1.3 g. of potassium hydroxide (85% pure) in 26 ml. ofdiethyleneglycol ethyl n-butyl diether were heated for one hour at 150C., while stirring. Then the reaction mixture was cooled to 10 C. whilestirring vigorously, 2 g. of Z-nitropropane were added, and the stirringwas continued for one hour at 20 C. 4.4 g. of l-bromo-3,7-dimethyl-2,6-octadiene were then added, and the re action mixturewas stirred for 15 hours at 25 30 C. The mixture was diluted with 80 ml.of water and worked up as described in- Example 1, yielding 3.1 g; of3,7-dimethyl-2,6-octadien-l-al.

Example 6 10 g. of 2-nitropropane were introduced slowly, while stirringand cooling, into a solution of 3.9 g. of potassium in ml. of t-butanol.The mixture obtained was mixed quickly with 23.1 g. ofl-bromo-3,7-dimethyl-2,6- nonadiene and the reaction mixture was stirredfor 20 hours at 25 C. Then the reaction mixture was poured into 200 ml.of ice water, and the mixture was extracted with petroleum ether. Thepetroleum ether extract was washed with dilute aqueous. sodium hydroxidesolution and with water, dried over sodium sulfate, and the solvent wasdistilled off. There were thus obtained 16.6 g. of3,7-dimethyl-2,G-nonadien-l-al, having an ultraviolet absorption maximumat 232 m (in petroleum ether). Upon purification by distillation invacuo, the material had B.P. 70 C./0.15 mm, n =1.483. This aldehyde hada fine fragrance reminiscent of citrus fruits.

The allylic halide used as starting material in this example,1-bromo-3,7-dimethyl-2,6-nonadine, can be made by the followingprocedure:

600. g. of 3-methyl-1-penten-3-ol were cooled to 15 C. with an ice bath,then 1800 ml. of concentrated aqueous hydrochloric acid (37% by weightHCl) were poured into the reaction vessel. The mixture was stirred for30 minutes. The oil, comprising essentially l-chloro-3-methyl-2-pentene, was separated, washed three times with 500 ml. ofwater and tried over calcium chloride.

Four liters of benzene, 104.0 g. of ethyl acetoacetate and 378 g. ofsodium methylate were stirred into a 12 liter flask. 696 g. of1-chloro-3-methyl-2 4pentene as produced in the preceding paragraph wereadded from a separatory funnel in 2 hours at 60 C. The stirring was thencontinued at 60 C. overnight.

The mixture was diluted with four liters of water. The oil was separatedand the benzene was distilled oil? under vacuum. The thick residue,3-carbethoxy-6-methyl-5- octen-Z-one, was placed in a 5 liter flask with2 liters of ethyl alcohol, 1 liter of water and 500 g. of potassiumhydroxide. This was stirred for two hours, then allowed to standovernight, thereby forming the potassium salt of3-carboxy-6-methyl-5-octen-2rone.

Concentrated hydrochloric acid was added to the stirred. reactionmixture from a separatory funnel until strongly acid. The oil layer wasremoved, and the aqueous portion was extracted with one liter ofbenzene. The combined oils were water-washed and fractionated to yield6-methyl-5-octe-n-2-one, distilling at 65 C./ 10 mm., n =1.4412.

84 g. of metallic sodium were dissolved in- 3 liters of liquid ammonia.Acetylene was bubbled into the stirred solution until its color changedfrom blue to white. 420 g. of 6-methyl-5-octen-2-one were dissolved in500 ml. of diethyl ether and dropped into the stirred reaction mixturein one hour. Stirring was continued for 3 hours while a slow stream ofacetylene was bubbled in. The acetylene was then stopped, but thestirring was con- 7 tinued for about 15 hours. The ammonia was thendistilled off and the residue in the reaction vessel was washed with 2liters of 5% aqueous sulfuric acid. The product was water-washed, driedover anhydrous calcium sulfate and fractionated to yield3,7-dimethyl-6-nonen-1-yn-3-ol, distilling at 89 C./ 10 mm., n =1.4612.

300 g. of 3,7-dimethyl-6-nonen-l-yn-3-ol, 30 g. of 5% leadpalladium-calcium carbonate catalyst [Lindlar, Helvetica Chimica Acta35, 46 (1952)], and 300 ml. of petroleum ether were placed in a flaskprovided with a stirrer and hydrogenated at 2530 C. at one atmospherehydrogen pressure until 1.9 mols of hydrogen were consumed.Fractionation of the product gave 3,7-dimethyl-1,6-nonadien-3-ol,distilling at 132 C./ 86 mm., n =1.4603.

110 g. of 3,7-dimethyl-1,6-nonadien-3-ol, dissolved in 500 ml. ofabsolute ether, were cooled to -10 C. To this were added slowly withstirring 85 g. of phosphorus tribromide, at such a rate as to keep thetemperature in the reaction vessel below C. The addition required onehour. The mixture was stirred an additional hour at C. and then pouredinto cold water. The organic layer was separated, washed with sodiumhydrogen carbonate solution and with water, then dried over sodiumsulfate. The solvent was driven off, yielding 150 g. of1-bromo-3,7-dimethyl-2,6-nonadiene, n =1.493.

Example 7 44 g. of potassium hydroxide were dissolved in 70 ml. ofwater, the solution was diluted with 450 ml. of isopropanol, whereupon64 ml. of 2-nitropropane were added slowly, with stirring, at 20 C. Themixture was stirred further for 5 minutes and 164 g. of 1-bromo-3,7,9-trimethyl-2,6-decadiene were added at once. The temF perature wasmaintained at about 40-45 C. Once the exothermic reaction was over, themixture was heated to 45 C. for 20 minutes, then cooled down to 20 C.,diluted with water and extracted with petroleum ether. The petroleumether solution was washed with normal sodium hydroxide solution and with1% sodium hydrogen carbonate solution, dried over sodium sulfate andconcentrated by distilling off the solvent. Thus were obtained 129 g. ofcrude 3,7,9-trimethyl-2,6-decadien-l-al, which, when purified bybisulfite extraction and distillation yielded 95 g. of pure product;B.P.=102 C./0.8 mm., n =l.4776; absorption maximum in the ultravioletspectrum at 238 my. in alcohol. This aldehyde had a fine odorreminiscent of citrus fruits.

The allylic halide used as starting material in this example,1-bromo-3,7,9-trirnethy1-2,6-decadiene, can be prepared by the followingprocedure:

438 g. of 3,5-dimethyl-1-hexen-3-ol were stirred with 1500 ml. ofconcentrated aqueous hydrochloric acid (37% by weight HCl concentration)at room temperature for 30 minutes. The oil layer was separated, washedtwice, each time with 500 ml. of water, and dried over calcium chloride.The product obtained, 1-chloro-3,5-dimethyl-2- hexene, had n =l.448.

In a five liter flask there were placed three liters of benzene, 429 g.of ethyl acetoacetate and 162 g, of sodium methylate. 428 g. of theproduct of the preceding paragraph, 1-chloro-3,5-dimethyl-2-hexene, wereadded at 60 C. within 30 minutes, and stirring was continued for sixhours at 60 -70 C. The reaction mixture was washed with two liters ofwater and the benzene was distilled off under a vacuum of 100 mm. toyield 3-carbethoxy- 6,8-dimethyl-5-nonen-2-one as a straw-colored oil.

The entire quantity of 3-carbethoxy-6,8-dimethyl-5- nonen-2-one producedabove was dissolved in 2 liters of ethyl alcohol. To this were added 200g. of solid potassium hydroxide and 200 ml. of water. The mixture wasstirred for 4 hours at 40 50 C. To the resulting solution of thepotassium salt of 3-carboxy-6,8-dimethyl-5- nonen-2-one was then addedconcentrated aqueous hydrochloric acid (37% by weight HCl) from ascparatory fun- S nel until the solution was strongly acid. Thirtyminutes were required for the addition. The solution was then stirred anadditional hour at 50 C.

The reaction mixture was diluted with two liters of water and the oillayer was removed by means of a separatory funnel. The aqueous portionwas extracted with 500 ml. of benzene. The combined oils were washedneutral with water and fractionated. The product, 6,8-dimethyl-S-nonen-Z-one, distilled at 120 C./35 mm., n =1.4432.

In 1.5 liters of liquid ammonia there were dissolved 41.4 g. of metallicsodium. Acetylene gas was passed into the blue colored solution, untilthe color changed to white. The addition of acetylene was continued foran extra 30 minutes. Then a solution of 252 g. of 6,8-dimethyl-5-nonen-2-one, dissolved in 250 ml. of ethyl ether, was dropped in within45 minutes. The stirring was continued for 15 hours while a slow streamof acetylene was bubbled into the reaction mixture.

The ammonia was thereupon evaporated from the reaction mixture with theaid of a slow stream of nitrogen. The residue was poured into 2 litersof 5% sulfuric acid. The oil layer was removed and washed neutral withwater. On fractionation, 3,7,9-trimethy1-1-decyn-6-en-3r 01 was obtainedin a fraction distilling at 72 C./ 0.35 mm., n =1.4598.

189 g. of 3,7,9-trimethyl-1-decyn-6-en-3-ol were diluted with an equalvolume of petroleum ether and placed in a flask with 18.9 g. of 5%lead-palladium-on-calcium carbonate catalyst [Lindlar, Helvetica ChimicaActa 35, 446 (1952)]. This was hydrogenated at one atmosphere gaugehydrogen pressure until 0.97 mol of hydrogen was consumed. Onfractionation of the reaction mixture, there was obtained3,7,9-trirnethyl-1,6-decadien-3-ol, distilling at 129 C./20 mrn., n=l.4592.

127 g. of 3,7,9-trimethyl-1,6-decadien-3-ol, dissolved in 500 ml. ofabsolute ether, were cooled to 10 C. To this were added slowly, withstirring, g. of phosphorus tribromide, at such a rate as to keep thetemperature in the reaction vessel below 0 C. The addition required onehour. The reaction mixture was stirred an additional hour at 5 C. andthen poured into cold water. The organic layer was separated, washedwith sodium hydrogencarbonate solution and with water, then dried oversodium sulfate. The solvent was driven off, yielding 164 g. of1-bromo-3,7,9-trimethyl-2,6-decadiene, n =1.487.

Example 8 10 g. of 2-nitropropane were added slowly, while stirring andcooling to 1020 C., to a mixture of 6.9 g. of potassium hydroxide (85%pure), 8 ml. of water and 30 ml. of acetonitrile. Then a solution of21.9 g. of 1- bromo-3,7-dimethyl-2-octene in 50 ml. of acetonitrile wasadded, and the mixture was stirred thoroughly for six hours at 25-30 C.The reaction mixture was then worked up in the manner described inExample 1, yielding 15.4 g. of 3,7-dimethyl-2-octen-l-al. Uponpurification of the latter by distillation in vacuo, a purified form ofproduct was obtained having B.P. 8687 C., n =1.462. This aldehydepossessed a fragrance reminiscent of citrus.

Example 9 37.6 g. of 2-(2,6,6-trimethyl-l-cyclohexylidene)ethyl bromidein ml. of dimethylformamide were mixed at once, while stirring andcooling to 25 -35 C., with a solution of 11.3 g. of potassium hydroxide(85% pure) and 16.2 g. of 2-nitropropane in 15 ml. of water and 50 ml.of dimethylformamide. The reaction mixture was stirred for 15 hours atabout 25 C. and worked up in the manner described in Example 1. Therewere thus obtained 25 g. of2,6,6-trimethy1-1-cyclohexylidene-acetaldehyde having an absorptionmaximum in the ultraviolet spectrum at 236.5 my. (in petroleum ether).This product was purified by distillation and chromatography. Itsphenylsemicarbazone had M.P. C. and ultraviolet absorption maxima at 241my and 284.5 mg (in petroleum ether). This aldehyde can be converted to[i-carotene by the method disclosed by Islet and collaborators at theXIV International Congress of Pure and Applied Chemistry in Zurich,1955, as described in the Handbook of the Congress, Item 280.

The allylic halide used as starting material in this example, i.e.2-(2,6,6-trimethyl-l-cyclohexylidene)ethylbromide, can be prepared bythe following procedure:

Acetylene was introduced into a solution of 1.4 g. of lithium in 700 ml.of liquid ammonia, until no further reactiontook place. Then 24.5 g. of2,6,6-trimethyl- 1- cyclohexanone were added and the mixture was stirredfor 25 hours, taking precautions to exclude moisture. At the end of thistime, 20 g. of ammonium chloride were added, and then the ammonia wasdriven oif. The residue was taken up in diethyl ether, washed with waterand dried over sodium sulfate; the ether was driven off and the residuewas distilled in vacuo. There were thus obtained 28 g. of1-ethinyl-2,6,6-t1irnethyl-1-cyclohexanol, B.P. 8183 C./ mm.

The latter material (28 g.) was dissolved in 150 ml. of petroleum ether,and 0.3 ml. of quinoline and 3 g. of palladium-lead-calcium carbonatecatalyst [Lindlar, Helvetica Chimica Acta 35, 446 (1952)], was added,and elemental hydrogen was introduced under a slight hydrogenoverpressure until no further hydrogen was taken up (approximately 1 molwas absorbed). Then the catalyst was filtered off, and the filtrate wasconcentrated, yielding 28.3 g. of2,6,6-trimethyl-l-vinyl-l-cyclohexanol, which were subjected to furtherreaction without being purified.

The entire amount of the last mentioned product was dissolved in 60 ml.of dry benzene and stirred for one hour at 50-60 C. with a solution of16.6 g. of phosphorus tribrornide in 20 ml. of benzene. The reactionmixture was then poured upon ice, the organic layer was separated,washed with sodium bicarbonate solution and then with water, dried oversodium sulfate, and then the solvent was driven off, yielding 37.6 g. of2-(2,6,6-trimethyl-l-cyclohexylidene) ethyl bromide.

Example 10 1 g. of 2-nitropropane was added slowly, while stirring andcooling with ice, to 0.66 g. of potassium hydroxide (85% pure) in 0.7ml. of water and 3 ml. of dimethylformamide. The solution obtained wasslowly added, while stirring and cooling to 20-30 C., to a solution of2.9 g. of 2-(4-acetoxy-2,6,6-trimethyl-1-cyclohexylidene)- ethyl bromidein 10 ml. of dimethylformamide. The reaction mixture was then stirredfor hours at room temperature and worked up inthe manner described inExample 1. There were thus obtained 2.4 g. of 4-acetoxy-2,6,6-trirnethyl-1-cyclohexylidene acetaldehyde, having anultraviolet absorption maximum at 231 m (in petroleum ether). Theproduct was purified by chroma tography. Its phenylsemicarbazone hadM.P. 183-185 C. and ultraviolet absorption maxima at 236 m and 283 my(in petroleum ether).

The allylic halide used as starting material in this ex ample, i.e.2-(4-acetoxy-2,6,6-trimethyl 1 cyclohexylidene)ethyl bromide, wasprepared by the following pro cedure:

138 g. of 2,6,6rtrimethyl-1-cyclohexen-4-one made from isophorone byknown procedure in 50 ml. of glacial acetic acid were stirred for twohours at 0-10 C. with 160 ml. of peracetic acid (containing 530; mg. ofperacetic acid per ml.) and the mixture was allowed to stand overnightat C. Then, while adding ice, the reaction mixture was made weaklyalkaline (pH about 8) by adding 30% aqueous NaOH solution, and the reac*tion mixture was shaken for one hour at 20 C. Then the mixture wasextracted twice, each time with 800 ml. of diethyl ether, and the ethersolutions were washed once with 200ml. of saturated ammonium chloridesolution. The ether solutions were combined and dried over sodiumsulfate, the solvent was driven off, and the resi* due was distilled inhigh vacuum. A forerun passed over between 70 and C., and then2,6,6-trimethyl- 2-cyclohexen-1-ol-4-one was obtained as an almostcolorless oil having B.P. llO-1l2 C./O.1 mm., n =1.501, U.V. maximum at226 m,

(E}=l1l0 in petroleum ether solution) after standing for some time. Thephenylserriicarbazone had M.P. 189-190 C., U.V. maxirna at 240.5 Hip.and 285 111,14

(E=807 and 778 in ethanol) To 154 g. of2,6,6-trimethyl-2-cyclohexen-1-ol-4-one in 200 ml. of glacial aceticacid and 500 ml. of water were quickly added dropwise 70 g. of chromicanhydride in 200 ml. of water, while stirring and cooling, so that thetemperature did not rise above 30 C. The mixture was then stirredovernight at 20 C. Then the reaction mixture was saturated with ammoniumchloride and was ex tracted with 1000 ml. of petroleum ether (boilingrange 30-60 C.). The aqueous layer was again extracted in a secondseparatory funnel with 500 ml. of petroleum ether. The petroleum ethersolutions were washed with saturated ammonium chloride solution to whicha little ammonia had been added, and then with pure saturated ammoniumchloride solution. The washed extracts were dried over sodium sulfateand the solvent was driven oil. The product,2,6,6-trimethyl-2-cyclohexene-1,4-di one, was distilled under a waterpump vacuum; B.P. 92-94 C./11 mm., a yellow oil which solidified tocrystalline form in the refrigerator, n =1.490, U.V. maximum at 238 m,

(E{=94-.2 in petroleum ether) The phenylsemicarbazone had M.P. 190 C.,then resolidified and melted again at 230 C., U.V. maxima at 242.5 mgand 325.5 m,

(E=875 and 580 in ethanol) 65 g. of2,6,6-trimethyl-2-cyclohexene-1,4-dione in 250 ml. of glacial aceticacid were slowly reacted with g. of zinc dust, while stirring, so thatthe temperature did not rise above 50 C. Then the reaction mixture wasstirred for an additional period of one hour. The reaction mixture wasfiltered, diluted with 1000 ml. of water and then saturated withammonium chloride. The mixture was extracted twice, each time with 800ml. of petroleum ether (boiling range 30-60 C.). The petroleurn ethersolutions were washed with 300 ml. of saturated ammonium chloridesolution to which some ammonia was added, and then were washed with puresaturated ammonium chloride solution. (In case a portion of the productcrystallizes from the petroleum ether solution, it is filtered 011?, thecrystalline material is dissolved in diethyl ether, then the diethylether solution is washed as indicated above, dried over sodium sulfateand then combined with the petroleum ether solution.) The solvent wasdriven off until the product 2,6,6-trimethyl- 1,4-cyclohexanedionestarted to crystallize out; colorless needles, M.P. 63 65 C., having noabsorption maximum in the ultraviolet spectrum between 220 m and 280 mThe phenylsemicarbazone had MP 218220 C., U.V. maximum at 250 mu (E 1030in ethanol) 10 g. of 2,6,6-trimethyl-1,4-cyclohexanedione, dissolved in50 ml. of methanol, were shaken with elemental hydrogen, at atmosphericpressure and at room temperature and in the presence of 1 g. of Raneynickel, until approximately 1.475 ml. of hydrogen were taken up. Thenthe catalyst was filtered ofi, the solvent was driven 01?, and theresidual crude 4-hydroxy-2,6,6-trimethyl-l-cyclohexanone (10 g.) wasrefluxed for two hours with 20 g. of acetic anhydride. The reactionmixture was poured upon 50 g. of ice and the whole was stirred overnightat room temperature. Then the reaction mixture was extracted withpetroleum ether, the solvent was removed from the extract, and theresidue was distilled in high vacuum, yielding 11 g. of4-acetoxy-2,6,G-trimethyl-l-cyclohexanone as a viscous oil having B.P.90-91 C./0.2 mm., n ='1.4560.

20 g. of the last mentioned product were added dropwise, over a periodof 2 hours, to a solution of lithium acetylide prepared by introducingacetylene into a solution of 0.76 g. of lithium in 150 ml. of liquidammonia. In order to complete the reaction, the reaction mixture wasstirred for about 15 hours. At the end of this time, 6 g. of ammoniumchloride were cautiously added, and then the ammonia was driven off. Theresidue was taken up in diethyl ether, then the solvent was driven OE,and the residue was crystallized from petroleum ether, yielding4-acetoxy-1-ethinyl-2,6,6-tri methyl-l-cyclohexanol as colorlesscrystals, B.P. 145 148 C.

10 g. of the latter product, in a mixture of 50 ml. of ethyl acetate and50 ml. of petroleum ether, were hydrogenated at normal pressure andtemperature in the presence of 1 g. of lead-palladium-calcium carbonatecatalyst [Lindlar, Helvetica Chimica Acta 35, 446 (1952)], and 0.2 ml.of quinoline, until 1.000 ml. of hydrogen was taken up. Then thecatalyst was filtered ofi, the solvent was driven off, and the residuewas crystallized from petroleum ether, yielding 4-acetoxy-2,6,6-trimethyl-l-vinyl l-cyclohexanol, white needles, M.P. 178-180 C.

22.6 g. of the last mentioned product, dissolved in 100 ml. of absolutebenzene, were stirred with 10 g. of phosphorus tribromide in 50 ml. ofabsolute benzene for 30 minutes at 60 C., taking precautions to excludemoisture. Then the reaction mixture was poured upon ice and the wholewas extracted with petroleum ether. The extract was washed with water,then the solvent was driven off, yielding the desired product2-(4-acetoxy- 2,6,6-trimethyl-l-cyclohexylidene)ethyl bromide, which wasused without further purification.

Example 11 56 g. of 2-nitropropane were added slowly to 39 g. ofpotassium hydroxide (85% pure) in 50 ml. of water, while stirring andcooling to 25 C. The solution obtained was introduced slowly, whilestirring and cooling to 2030 C., into a solution of 122 g. of l-bromo-3,7-dimethyl-2,6-octadiene in 500 ml. of acetone, and the reactionmixture was stirred thoroughly for 6 hours at room temperature. Then amixture of 40 ml, of aqueous sodium hydroxide solution (containing 30%by weight NaOH) and 200 ml. of water were added, while cooling, and thewhole was stirred 15 hours longer at room temperature. The reactionmixture was then diluted with water and the reaction product wasextracted with petroleum ether. The petroleum ether extract was washedwith water, dried over sodium sulfate, and the solvent was distilledofi. The residue was distilled in vacuo, yielding 65 g. of6,10-dimethyl-3,5,9-undecatrien-2-one, B.P. 85 87 C./ 0.04 mm., n=1.5297; ultraviolet absorption maximum at 292 III/1. (in ethanol).

10 g. of 6,-10-dimethyl-3,5,9-undecatrien-2-one were dissolved in 25 ml.of dry benzene. While stirring and cooling to 35 C., boron trifluoridewas introduced into the solution until about 3 g. of boron trifluoridewere absorbed. The stirring was continued for 15 minutes at 15 C., andthen the reaction mixture was poured onto ice. The reaction mixture wasadjusted to pH 10 with 3 N aqueous sodium hydroxide solution, theaqueous layer was separated, washed with concentrated aqueous sodiumhydroxide solution and then with saturated sodium bicarbonate solution,and was dried over anhydrous potassium carbonate. The benzene was drivenoff and the residue Was distilled in a high vacuum, yieldi2 ing4-(2,6,6-trimethyl-2-cyclohexen-l-yl)-3-buten-2-one as a colorless oil.This ketone had a pleasant fragrance reminiscent of violets.

Example 12 6.9 g. of potassium hydroxide were dissolved in 11 ml. ofwater, diluted with 70 ml. of isopropanol, whereupon 9.8 g. of2-nitropropaue were added with stirring at 20 C. The mixture was stirredfor further 5 minutes and 21.7 g. of 1-bromo-3,7-dimethyl-2,6-octadienewere added at once. The temperature was maintained at 4045 C. Once theexothermic reaction was over, the mixture was heated to 45 C. for 20minutes, then cooled down to 20 C., and diluted with water. The oillayer which separated was taken up in ml. of acetone. While stirring andcooling, a solution of 7.2 ml. of aqueous sodium hydroxide solution(containing 30% by weight NaOH) in 44 ml. of water was added to theacetone solution, and the reaction mixture was stirred for 15 hours atroom temperature. The reaction mixture was then worked up as in Example11, and the condensation product obtained was distilled in vacuo,yielding 11.5 g. of 6,10-dimethyl-3,5,9-undecatrien-2-one, B.P. 85-87C./0.04 mm.; semicarbazone M.P. 141- 142 C.

8.2 g. of 6,10-dimethyl-3,5,9-undecatrien-2-one were dissolved in 10 ml.of petroleum ether, and the solution was added slowly, at minus 5 C.,while stirring, to a mixture of 15 ml. of glacial acetic acid and 34 g.of concentrated sulfuric acid. The reaction mixture was stirred for 15minutes at minus 5 C., and for 20 minutes at plus 10 C., and then waspoured upon ice. The organic product was extracted with petroleum ether,the extract was washed neutral, dried and the solvent was driven 0E. Theresidue was distilled in high vacuum, yielding 6.1 g. of4-(2,6,6-trimethyl-l-cyclohexen-1-yl)- 3-buten-2-one, B.P. 9497 C./0.9mm., n =l.5l9; semicarbazone B.P. 148-149 C. This ketone had a pleasantodor reminiscent of violets.

Example 13 130 g. of 1-bromo-3,6,7-trimethyl-2,6-octadiene in 500 ml. ofacetone were reacted in the manner indicated in Example 11 with asolution of the potassium salt of 2-propane-nitronic acid (prepared from56 g. of 2-nitropropane, 39 g. of potassium hydroxide [85% pure] and 50ml. of water) and the reaction mixture was then mixed with 40 ml. ofaqueous sodium hydroxide solution (containing 30% by weight NaOH) in 200ml. of water. The reaction mixture was worked up in the manner describedin Example 11. Upon distillation in vacuo, there were obtained 62 g. of6,9,10-trimethyl- 3,5,9-undecatrien-2-one, B.P. 110 C./0.5 mm., n=1.5305, semicarbazone (from methanol) M.P. 169-172 C.

The 6,9,10-trimethyl-3,5,9-undecatrien-2-one was cyclized by means ofboron trifluoride in the manner described in Example 11, yielding4-(2,5,6,6-tetramethyl- 2-cyclohexen-1-yl)-3-buten-2-one, B.P. 8687C./0.5 mm., n =1.499; phenylsemicarbazone M.P. 171172 C This ketone hada pleasant fragrance reminiscent of His.

The allylic halide used as starting material in this example, i.e.1-bromo-3,6,7-trimethyl-2,6-octadiene, was prepared by the followingprocedure:

168 g. of 3,6,7-trimethyl-1,6-octadien-3-ol, dissolved in 500 ml. ofabsolute petroleum ether, were cooled to -5 C. To this were addedslowly, with stirring, 121 g. of phosphorus tribromide at such a rate asto keep the temperature in the reaction vessel below 0 C. The additionrequired one hour. The mixture was stirred an additional hour at 5 C.and then poured into cold water. The organic layer was separated, washedwith sodium hydrogencarbonate solution and with water, then dried oversodium sulfate. The solvent was driven ofi,

yielding 220 g. of 1-bromo-3,6,7-trimethyl-2,6-octadiene, n =l.496.

Example 14 239 g. of potassium hydroxide were dissolved in 380 ml. ofwater, the solution was diluted with 2400 ml. of

isopropanol and 346 ml. of 2-nitropropane were added slowly, whilestirring, at 20 C. The mixture was stirred for further 5 minutes and 900g. of 1-bromo-3,7,11- trimethyl-Z-dodecene were added at once. Thetemperature was maintained at about 4045 C. Once the exothermic reactionwas over, the mixture was heated to 45 C. for further 20 minutes, cooleddown to 20 C., diluted with water and extracted with petroleum ether.The petroleum ether solution was washed with normal sodium hydroxidesolution and with 1% sodium hydrogen carbonate solution, dried oversodium sulfate and concentrated by evaporating the solvent. 680 g. ofcrude 3,7,1l-trimthyl-Z-dodecen-l-al were obtained. This aldehyde waspurified by bisulfite extraction and by distillation; B.P. 85 C./ 0.05mm.; ultraviolet spectrum absorption maximum at 239 my in alcohol; n=1.465.

Example 15 A mixture of 2.45 g. of potassium hydroxide, 30 ml. ofacetone and 3.5 g. of Z-nitropropane were mixed and stirred until thereaction was complete, then g. of1-bromo-3,7,11-trimethy1-2,6,l0-dodecatriene were added and the mixturewas stirred further at 40 C. for one hour. The reaction mixture wasdiluted with water, extracted with petroleum ether, whereupon thepetroleum ether solution was washed with dilute aqueous sodium hydroxidesolution, dried over sodium sulfate and freed from the solvent bydistillation. There were obtained 8.3 g. of3,7,1l-trimethyl-2,6,IO-dodecatrien-l-al, which was purified bychromatography and distillation;

ultraviolet absorption maximum at 231 my. in petroleum ether.

Example 16 A mixture of 16.5 g. of potassium hydroxide, 7 ml. of water,200 ml. of acetone and 30 g. of 2-nitropropane was stirred until thereaction was complete, then 66 g. of(2-isopropyl-S-methylcyclohexylidene)ethyl bromide were added, thereaction mixture was stirred for 4 hours at 3035 C. and then for 10minutes at 55 C. It was then diluted with water, extracted withpetroleum ether, whereupon the petroleum ether solution was washed withdilute sodium hydroxide solution and with water, dried over sodiumsulfate and freed from the solvent by distillation. There were obtained52 g. of (2-isopropyl-5 methyl cyclohexylidene) acetaldehyde, which waspurified by distillation; B.P. 80 C./0.1 mm.; n 1.495; ultravioletabsorption maximum at 235 my in petroleum ether.

Example 17 As described in Example 16 for(2-isopropyl-5-methylcyclohexylidene)ethyl bromide, 67.5 g. of(2,2,6,6-tetramethylcyclohexylidene)ethyl bromide were reacted with amixture of 16.5 g. of potassium hydroxide, 7 ml. of water, 200 ml. ofacetone and 30 g. of 2-nitr0propane. When working up the reactionmixture as described in the preceding example, 57 g. of(2,2,6,6-tetramethylcyclohexylidene)acetaldehyde were obtained. Thisaide hyde was purified by distillation; B.P. 68 C./0.14 mm.; :1 =1.502;ultraviolet absorption maximum at 240 my in petroleum ether.

Example 18 45 g. of 3-rnethyl-crotyl bromide were added within minutes,while stirring and cooling to 2426 C., to a solution of 18 g. ofpotassium hydroxide and 29 g. of 2-nitropropane in 30 ml. of water and50 ml. of dimethylformamide. The reaction mixture was stirred anadditional hour, while cooling to 27-30 C., and

then poured into 100 ml. of ice water, and the mixture was extractedwith petroleum ether. The petroleum ether extract was washed with diluteaqueous sodium hydroxide solution, dried over sodium sulfate, and thesolvent was distilled oif. There was thus obtained 16 g. of3-methylcrotonaldehyde. Upon purification by distillation in vacuo, thematerial had B.P. 39-40 C./30 mm. The 2,4-dinitrophenylhydrazone of thisaldehyde had M.P. 183 -l84 C. and an ultraviolet absorption maximum at382 mp (in chloroform).

This application is a division of our copeuding application Serial No.605,462, filed August 22, 1956, now abandoned.

We claim:

1. A process of making an c p-unsaturated aldehyde which comprisesmixing a 3,3-disubstituted allyl halide having the formula wherein thesymbol X represents a halogen selected from the group consisting ofchlorine and bromine, and the symbol group B=C= represents adisubstituted methylene radical selected from the group consisting ofdialkylmethylene, alkylalkenylmethylene, cycloalkylidene andcycloalkylidene substituted in the ring only by at least one substituentof the class consisting of lower alkyl, lower alkoxy, lower alkanoyloxy,0x0 and ethylenedioxy, with an alkali metal salt of a loweralkanenitronic acid.

2. A process of making a monoolefinic c p-unsaturated aldehyde whichcomprises mixing a 3-alkylcrotyl halide, the halide being selected fromthe group consisting of the chloride and the bromide, with an alkalimetal salt of a lower alkanenitronic acid in the presence of an inertliquid diluent at temperatures between about -10 C. and C.

3. A process of making a polyolefinic exp-unsaturated aldehyde whichcomprises mixing a 3-alkenylcrotyl halide, the halide being selectedfrom the group consisting of the chloride and the bromide, with analkali metal salt of a lower alkanenitronic acid in the presence of aninert liquid diluent at temperatures between about 10 C. and 80 C.

4. A process of making a cyclic o e-unsaturated aldehyde which comprisesmixing 2-(2,6,6-trimethyl-1-cyclohexylidene) ethyl bromide with analkali metal salt of a lower alkanenitronic acid in the presence of aninert liquid diluent at temperatures between about -10 C. and 80 C.

5. A process of making 3,7-dimethyl-2,6-octadien-l-al which comprisesmixing 1-bromo-3,7-dimethyl-2,6-octadiene with an alkali metal salt of2-propanenitronic acid in the presence of an inert liquid diluent attemperatures between about -10 C. and 80 C.

6. A process of making 3,7-dimethyl-2,6-octadien-l-al which comprisesmixing 1-chloro-3,7-dimethyl-2,6-octadiene with an alkali metal salt of2-propanenitronic' acid in the presence of an inert liquid diluent attemperatures between about -10 C. and 80 C.

7. A process of making 2,6,6-trimethyl-l-cyclohexylideneacetaldehydewhich comprises mixing 2-(2,6,6-trimethyl-l-cyclohexylidene)ethylbromide with an alkali metal salt of 2-propanenitronic acid in thepresence of an inert liquid diluent at temperatures between about -10 C.and 80 C.

References Cited in the file of this patent UNITED STATES PATENTS Chuitet al June 10, 1902 OTHER REFERENCES

1. A PROCESS OF MAKING AN A,B-UNSATURATED ALDEHYDE WHICH COMPRISESMIXING A 3,3-DISUBSTITUTED ALLYL HALIDE HAVING THE FORMULA B=C=CH-CH2-XWHEREIN THE SYMBOL X REPRESENTS A HALOGEN SELECTED FROM THE GROUPCONSISTING OF CHLORINE AND BROMINE, AND THE SYMBOL GROUP B=C= REPRESENTSA DISUBSTITUTED METHYLENE RADICAL SELECTED FROM THE GROUP CONSISTING OFDIALKYLMETHYLENE, ALKYALKENYLMETHYLENE, CYCLOALKYLIDENE ANDCYCLOALKYLIDENE SUBSTITUTED IN THE RING ONLY BY AT LEAST ONE SUBSTITUENTOF THE CLASS CONSISTING OF LOWER ALKYL, LOWER ALKOXY, LOWER ALKANOYLOXY,OXO AND ETHYLENEDIOXY, WITH AN ALKALI METAL SALT OF A LOWERALKANENITRONIC ACID.